Near-infrared fluorescence imaging with indocyanine green for quantification of changes in tissue perfusion following revascularization.

OBJECTIVES: Current diagnostic modalities for patients with peripheral artery disease (PAD) mainly focus on the macrovascular level. For assessment of tissue perfusion, near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) seems promising. In this prospective cohort study, ICG NIR fluorescence imaging was performed pre- and post-revascularization to assess changes in foot perfusion. METHODS: ICG NIR fluorescence imaging was performed in 36 patients with PAD pre- and post-intervention. After intravenous bolus injection of 0.1 mg/kg ICG, the camera registered the NIR fluorescence intensity over time on the dorsum of the feet for 15 min using the Quest Spectrum Platform®. Time-intensity curves were plotted for three regions of interest (ROI): (1) the dorsum of the foot, (2) the forefoot, and (3) the hallux. Time-intensity curves were normalized for maximum fluorescence intensity. Extracted parameters were the maximum slope, area under the curve (AUC) for the ingress, and the AUC for the egress. The non-treated contralateral leg was used as a control group. RESULTS: Successful revascularization was performed in 32 patients. There was a significant increase for the maximum slope and AUC egress in all three ROIs. The most significant difference was seen for the maximum slope in ROI 3 (3.7%/s to 6.6%/s, p < 0.001). In the control group, no significant differences were seen for the maximum slope and AUC egress in all ROIs. CONCLUSIONS: This study shows the potential of ICG NIR fluorescence imaging in assessing the effect of revascularization procedures on foot perfusion. Future studies should focus on the use of this technique in predicting favorable outcome of revascularization procedures.

A systematic review of the use of near-infrared fluorescence imaging in patients with peripheral artery disease.

OBJECTIVE: In the diagnosis of peripheral artery disease (PAD), the ankle-brachial index plays an important role. However, results of the ankle-brachial index are unreliable in patients with severe media sclerosis. Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) can provide information about tissue perfusion and has already been studied in oncologic, reconstructive, and cardiac surgery. For patients with PAD, this technique might give insight into skin perfusion and thereby guide treatment. We performed a systematic review of the literature on the use of NIR fluorescence imaging in patients with PAD. METHODS: PubMed, MEDLINE, Embase, and Cochrane were searched for articles and abstracts on the application of NIR fluorescence imaging using ICG as fluorescent dye in patients with PAD. Our search strategy combined the terms "fluorescence," "ICG," or synonyms and "peripheral artery disease" or synonyms. The extracted data included fluorescence parameters and test characteristics for diagnosis of PAD. RESULTS: Twenty-three articles were found eligible for this review using 18 different parameters for evaluation of the fluorescence signal intensity. NIR fluorescence imaging was used for four main indications: diagnosis, quality control in revascularization, guidance in amputation surgery, and visualization of vascular structures. For the diagnosis of PAD, NIR fluorescence imaging yields a sensitivity ranging from 67% to 100% and a specificity varying between 72% and 100%. Significant increases in multiple fluorescence parameters were found in comparing patients before and after revascularization. CONCLUSIONS: NIR fluorescence imaging can be used for several indications in patients with PAD. NIR fluorescence imaging seems promising in diagnosis of PAD and guidance of surgeons in treatment, especially in patients in whom current diagnostic methods are not applicable. Further standardization is needed to reliably use this modality in patients with PAD.

Severe Infrarenal Atheroma Load in Open Aortic Aneurysm Repair Is Not a Risk Factor for Postoperative Acute Kidney Injury.

BACKGROUND: Acute kidney injury (AKI) after open aortic repair is subject to multiple patient- and operation-related variables. Hostile neck morphology in open aneurysm repair is thought to contribute to this AKI risk postoperatively. The aim of this study was to evaluate if large neck atheroma is a possible risk factor in the postoperative development of AKI. METHODS: Retrospectively 137 patients were evaluated for neck atheroma and AKI incidence. Atheroma load measurements were performed by 2 different techniques. Results were compared, and secondly a univariate analysis was performed for multiple additional risk factors regarding AKI occurrence. RESULTS: Significant (>30%) neck atheroma was not associated with a higher risk for developing AKI (odds ratio [OR]: 1.81; 95% confidence intervals: 0.74-4.44). Overall incidence of AKI based upon Acute Kidney Injury Network criteria was 19.7%. In univariate analysis coronary artery disease and the presence of a renal artery stenosis were both significantly associated with AKI (OR: 2.38, 3.31, respectively) as well as the use of B-blockers and angiotensin converting enzyme inhibitors (OR 3.05, 2.48, respectively). CONCLUSIONS: Cross-clamping in case of significant neck atheroma during open aortic aneurysm repair is not associated with increased risk of AKI. Defining high-risk patients based on additional risk factors must be a part of preoperative patient selection.